Brugmansia candida and Cerbera odollam have been known as poisonous plants. The present study investigated the ovicidal activity of B. candida and C. odollam extracts against Aedes aegypti and Culex quinquefasciatus. B. candida leaves and C. odollam seed kernels were extracted by methanol, and then evaporated by rotary evaporator to obtain the dried extracts. The dried extracts with concentrations of 0.5 g/l, 1.0 g/l, and 2 g/l were diluted in the tap water and then eggs of A. aedes and C. quinquefasciatus were put on surface of those solutions. The hatch rate was observed until 5 days post treatment. The result showed that there was no significant difference of percent hatchability between A. aegypti and C. quinquefaasciatus at the end of observation for both extarcts, B. candida and C. odollam extracts. The percent hatchability of both eggs decreased with increasing the concentration of extracts. Both extracts exhibited high ovicidal activity against dengue and filarial vectors. However, the percent hatchability of A. aegypti and C. quinquefasciatus eggs for B. candida was significantly higher than that for C. odollam, suggesting that C. odollam is more toxic for mosquitoes’ eggs than B. candida. Overall, the data clearly suggest that B. candida and C. odollam are promising as an ovicidal agent against mosquitoes, A. aegypti and C. quinquefasciatus.